There are a host of ultrasonic water flow meter options to choose from in the market. Usually, there are two types of principles associated with this: Transit Time and the Doppler Principle.

The article explains the working principle of ultrasonic water flow meter and how can we choose the suitable flow meter depending on their applications.


To know more about ultrasonic flow meters, you can read the Visaya Article on Ultrasonic Basics

Ultrasonic water flow meter types

The principle of transit time is not complicated. Basically, we need to have two transducers. Both contain a piezoelectric crystal and they’re both responsible for transmitting and receiving the signal. That way, they change the statement.

Usually, the transducers will operate in the 1 -2 MHZ frequencies, the principle is based on the difference of time to an ultrasonic signal transmitted from the transducer across the pipe. It reads the receiving transducer in both directions- upstream and downstream. This time is compared.

Proline Prosonic Flow 92F Ultrasonic flow meter Loop powered flow transmitter with an inline sensor for the chemical industry
in the shop
Proline Prosonic Flow 92F

How does it work?

When we don’t have flow, the time to transmit and receive the ultrasonic signal will be the same. But when we have flow, we will have a difference of time to transmit and receive the signal. The disadvantage of this kind of ultrasonic water flow meter is the limitation with bubble and solids into the fluid. This condition can affect the calculation and cause an error of measurement.

The Doppler principle can use only a single sensor. This sensor has the transmitter and receiver sensor, as well as the piezoelectric crystal. The principle of work is single. Basically, the sound waves transmitted from the transducer will return with an altered frequency in which the fluid is in constant motion.

The change of frequency will be proportional to the velocity of the fluid and the transmitter will calculate the flow rate based on that information. The advantage of the Doppler principle is that even after having bubble and solid in the fluid,  we won’t have a problem with the flow measurement.

To know more ultrasonic flow meters,  can get in touch with our engineers and we will be happy to help.

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